I Am The Left Brain
by Jenn1984
Summary: Sherlock is logic, is analytical, is in control. Who Sherlock is evolves. John/Sherlock


For Pat, for her birthday. Love you so much.

Based on the Mercedes Benz left/right brain pictures.

I hope the story does the picture justice.

Disclaimer: I do not own Sherlock. Vague reference to adult themes.

* * *

><p>He is logic.<p>

One of the things Sherlock understands most of all is crime. Why people commit crime, how people commit crime, motivations and reasons for committing crime—the science behind it, he understands. Criminals have logical methods that he can deduce. They take certain paths, make predictable movements and fit into puzzles he so enjoys solving.

John is a puzzle, he thinks, watching the doctor make conversation at a crime scene with the busty blond witness. He knows all the right things to say to make her feel comfortable. John is very personable. Kind, he is, and predictable. The puzzle, however, is in why John isn't boring.

He casts a glance in Sherlock's direction, the smile of conversation still in his eyes and on his lips. Sherlock's mouth moves like a smile in response, without meaning to, which only makes John look at him more fondly before turning his attention back to the witness. Yes, John is a puzzle.

John is _not logical_.

Sherlock continues with Lestrade, deducing what he can, loud enough, he hopes, for John to hear. _Without being obvious_, he assures himself. It's working because John's face does what Sherlock loves so much; it brightens as he rattles off his conclusions and the reasoning behind them. Because he _is_ reason.

Without any hesitation, Sherlock admits in his mind that he could do this all day, every day for the rest of his life to make that look stay on John's face forever.

This is _not logical_.

He is _yearning_.

-x-

He is analytical.

They have left the crime scene, now comfortably close in the cab, normal as usual, until Sherlock realizes John's knee is touching his leg. He isn't sure why he is so conscious of it; they touch all the time. Why he thinks of it, why he needs to process and understand it makes his brain go into overdrive. It's confusing, but exciting and Sherlock feels a rush of—_something_.

Sherlock knows the words for every physical thing, and this is a physical thing, where he and John touch. That is physical, existing outside of Sherlock's overcrowded mind, and how Sherlock feels now is physical, is—a word he thinks he might be learning anew, from the inside, this time—

John puts his hand on Sherlock's, _touches him_, and says, "Stop overthinking it."

Sherlock's mind stills, obeying. No, agreeing. To not analyze. To—feel.

Sherlock feels it.

_Yearning_.

-x-

He is always in control.

Feelings are like drowning, Sherlock concludes. They're the equivalent to being suffocated by your own mind. Like your mind is a pillow held over your nose and mouth until you're gasping, _pleading_ for air.

Breathing, as it turns out, isn't boring at all. Breathing is John, and John is _spectacular_. But he is still a puzzle, and Sherlock is still trying to piece him together.

They are back at Scotland Yard and so is the scantily dressed witness. John is close to her, and she touches his shoulder playfully, flirting with him. Sherlock breathes faster, practically growling, just low enough to feel it in his throat and yet not loud enough to hear. As if he's made his own deduction, John laughs with her as he takes a step back. He glances at Sherlock to reassure him. Heaven help them, John is _reassuring him_ with eyes digging below walls strategically constructed around Sherlock's mind and heart.

Another puzzle piece doesn't fit, so Sherlock starts to mentally sift through the pieces again, regaining control of his breathing with each beautiful, passionate look John gives him. He thinks he is in control once more, but passion is not control.

He is _passion_.

-x-

He is language.

Sherlock's words are important. Everything he says, he says with meaning and for a reason, because he is a master of words. They aren't always very nice words, but he says them regardless. He wouldn't if they weren't important, except they always are.

And then there are times Sherlock shuts down the language center of his intensely smart brain to focus instead on that which he enjoys almost as much as puzzle-solving: music. Sherlock lives inside his brain for the most part, where it is precise and calculated and absolutely genius. Music draws him out, though, at random times during difficult cases or when he is craving something more than calculations and hypotheses and conclusions can give him.

The world is vivid and colorful when he plays, the violin like a soothing voice or a warm embrace. His music like John, who sits with eyes closed so he can be lost inside Sherlock's music; inside Sherlock's mind.

John's phone vibrates along the table, Sherlock notices, the name, "Joy" flashing blue with each buzz. The witness. His fingers falter only slightly in annoyance. John doesn't seem to notice, and Sherlock watches him move his head, tap his fingers on the armrest in time with the music Sherlock himself creates. No language, just movement. God, John is movement. Sherlock is no longer language.

He is movement.

-x-

He is accurate.

Everything makes sense in Sherlock's head. It's all linear and perfectly placed. Sharp, he thinks. They've returned to the crime scene on a hunch, though Sherlock knows they were brought back by his brilliance and logical deductions.

"I know he's still here," he whispers into John's ear. John takes in a shuddering breath and nods.

"Right. I'll go around back," John says quickly, moving off toward the building.

Sherlock's mouth twitches involuntarily at the thought of John inside his mind, knowing exactly what he plans before Sherlock explains what they're doing. John nods again, crouches low and takes out his gun. He becomes a soldier.

The door creaks loudly on the abandoned building as Sherlock pushes it slowly open, rotted wood splintering beneath his gloved fingers. He gets one foot over the threshold when a shot sounds behind the building, then another.

Sherlock doesn't freeze; he turns so harshly as soon as the first shot hits his ears that he tears his glove on the old wood, breaking skin on the pointed edges.

"John," he breathes.

_Please_. It means _please_.

Running faster than he imagined he could, Sherlock reaches the back of the building where John stands over a young man who is on the ground, clutching his bloody foot. Two guns are in either hand and John looks up, panting. Sherlock, also panting, smirks.

"Found him," John calls, returning the smile.

Sometimes, things don't go according to plan. Some things aren't accurate. Some things are beautifully spontaneous and creative.

He is creative.

-x-

He is practical.

Jealousy is something Sherlock understands in theory. People kill over it. A feeling, kill over _a feeling_, which is impractical and so utterly moronic.

Daybreak sees them back at Scotland Yard to close the case. The criminal has been apprehended, had his foot tended to, and sits now in an interrogation room with a defeated scowl across his face. Sherlock doesn't care what happens to him now; he's solved the crime and pieced together the puzzle. Now, he is presented with a new problem: Joy, the witness.

Impractical, jealous behavior suddenly makes more sense to him.

She identified the man in interrogation, and now stands painfully close to John, once again. Sherlock glares across the row of desks and makes a decision.

Practicality be _damned_.

He imagines exactly 14 different scenarios of how to deal with the situation before making it to the other side of the room.

Joy puts a piece of hair behind her ear. "Listen, John, I was wondering if you wanted—"

Sherlock reaches out and pulls John's arm into his, wrapping around him tightly. "He doesn't," he says pointedly.

John doesn't pull away, but stares up at Sherlock's face, momentarily stunned.

"I just thought—" Joy begins a second time, and Sherlock cuts her off again.

"He's not interested."

"Sherlock." John whispers his name like a warning. Sherlock smirks and Joy's face falls.

"Oh, my, I didn't realize," she says with a realization that makes Sherlock feel triumphant. "I feel so silly."

"No, no, you shouldn't—"

"You should."

"_Sherlock!_"

Countless apologies later, Sherlock and John, still arm in arm, walk slowly along the pavement in search of a cab to take them back to Baker Street.

"That wasn't very nice," John says, though Sherlock can hear the humor in his voice.

"I don't care about nice."

John stops and draws Sherlock's head down until they're noses brush against each other. "That a promise?"

And suddenly, he is _imagination_.

-x-

He is always in control, as long as he has John. Together, wrapped in each other, _real_. They are logic and passion and order and movement. He is John, and John is inside him.

Sherlock is the left brain, and John is the right. Two pieces which fit perfectly together, one brain. Whole.

They are exactly who they wanted to be.


End file.
